ok y'all.
So I was playing with horns tonight. plugged in a "finished" version of the ugly duckling right after an "unfinished" version. "finished" meaning the oil on the wood. the shiny stuff.
the sound totally changed. things sounded all chilled out on the finished version. even though everything else between the two pairs of horns was identical.
I have always noticed that the resonant frequency of the wall of the cabinet changed (fewer upper harmonics) (judged by knocking) after the application of the oil, but I had no idea that it made this much of a difference. the difference was subtle, yes. but at the same time, not. the effect was especially felt in the mid/high range.
So my question for everyone is why one would consider finishing the inside of the cabinet? Other than to "seal" the enclosure against long term moisture and subsequent glue break down. course, I have always figured that glue nowadays is so nice, that old school intricate (furniture) joinery, and internal moisture protection considerations can be left out of the equation to some degree.
I see around the web all sorts of different ways of finishing the insides and outsides of cabinets. I am asking for people's opinions on this matter. It is no doubt an issue that involves taste to some degree, but what sorts of effects can we imagine for ourselves?
obviously, I am asking about acoustic effects here. not visual effects of the finish.
In the musical instrument world, some hold the idea that the inside of the sound chamber should be left unfinished. Letting the roughness of the wood and little glue spots etc soak up any high frequencies. That is the thought I have prescribed to since playing with acoustic musical instruments on my own but eh, who the hell knows?
I mean, obviously, the type of finish product is important in and of itself, but where do we draw the lines? what happens with these things?
___TWO SECOND TWEAK___
It has come to my attention lately that there is a matter also, important to acheiving a chiller sound from full range drivers. I don't mean to give away trade secrets, but eh. that which you give away comes back in a different form, I suppose.
Basically, the torque of the driver mounting screws is of vital importance. I feel that it takes a whole lot less torque than most people think. If you have bent the area of the driver frame surrounding the screw, then back off!!!
For cast frame drivers, a more precise torquing method can be employed, involving a torque driver.
for me, though, i use just enough torque to secure the washer to the point that I cannot slide it around with my finger nail, and then just a smidge beyond that. obviously, it should be enough to provide an airtight seal, and to prevent anything from rattling (like the washers).
I have found myself tracking down early customers and doing torque tweak for them, or instructing them how to do so. It is SO important.
the drivers sound instantaneously broken in compared to before. I have found the effect of torque on frame to baffle to be VERY audible (in a subtle way). compared to a tightly cinched down driver, a thoughtfully mounted driver sounds like it has 40-100 hours more of break in, right out of the box. things only get better too...
Basically, it is all a matter of destressing components.
In other aspects of the horn, proper square, glue amount, clamp pressure, all amounting to not unnecessarily forcing a panel to warp during clamping. all this plays HEAVILY into the sound of a BLH. All this infinite variance though is scientifically frustrating enough to make any (relative) perfectionist like me go insane. All these considerations make me want to apprentice for a violin or harpsichord maker. Not that they would by definition know any better, but these sorts of things are hard to model, and hard to know the ultimate effect of without the hundreds of years of trial and error tweaking that musical instruments have been subjected to.
Also, I am wondering people's opinions on various driver mounting methods (t-nuts, screws, driver on the front of the baffle, on mounted on the back of the baffle, etc.)
alot of these little tweaks most manufacturers keep rather secret, as frankly, they are the hardest learned lessons (that is, if they even think about these sorts of considerations in the first place...) so I hope that people will step out for a minute and share advice.
anyways, thanks in advance for the hopeful discussion this will start.
Later,
Clark
blumenstein-ultra-fi.com
So I was playing with horns tonight. plugged in a "finished" version of the ugly duckling right after an "unfinished" version. "finished" meaning the oil on the wood. the shiny stuff.
the sound totally changed. things sounded all chilled out on the finished version. even though everything else between the two pairs of horns was identical.
I have always noticed that the resonant frequency of the wall of the cabinet changed (fewer upper harmonics) (judged by knocking) after the application of the oil, but I had no idea that it made this much of a difference. the difference was subtle, yes. but at the same time, not. the effect was especially felt in the mid/high range.
So my question for everyone is why one would consider finishing the inside of the cabinet? Other than to "seal" the enclosure against long term moisture and subsequent glue break down. course, I have always figured that glue nowadays is so nice, that old school intricate (furniture) joinery, and internal moisture protection considerations can be left out of the equation to some degree.
I see around the web all sorts of different ways of finishing the insides and outsides of cabinets. I am asking for people's opinions on this matter. It is no doubt an issue that involves taste to some degree, but what sorts of effects can we imagine for ourselves?
obviously, I am asking about acoustic effects here. not visual effects of the finish.
In the musical instrument world, some hold the idea that the inside of the sound chamber should be left unfinished. Letting the roughness of the wood and little glue spots etc soak up any high frequencies. That is the thought I have prescribed to since playing with acoustic musical instruments on my own but eh, who the hell knows?
I mean, obviously, the type of finish product is important in and of itself, but where do we draw the lines? what happens with these things?
___TWO SECOND TWEAK___
It has come to my attention lately that there is a matter also, important to acheiving a chiller sound from full range drivers. I don't mean to give away trade secrets, but eh. that which you give away comes back in a different form, I suppose.
Basically, the torque of the driver mounting screws is of vital importance. I feel that it takes a whole lot less torque than most people think. If you have bent the area of the driver frame surrounding the screw, then back off!!!
For cast frame drivers, a more precise torquing method can be employed, involving a torque driver.
for me, though, i use just enough torque to secure the washer to the point that I cannot slide it around with my finger nail, and then just a smidge beyond that. obviously, it should be enough to provide an airtight seal, and to prevent anything from rattling (like the washers).
I have found myself tracking down early customers and doing torque tweak for them, or instructing them how to do so. It is SO important.
the drivers sound instantaneously broken in compared to before. I have found the effect of torque on frame to baffle to be VERY audible (in a subtle way). compared to a tightly cinched down driver, a thoughtfully mounted driver sounds like it has 40-100 hours more of break in, right out of the box. things only get better too...
Basically, it is all a matter of destressing components.
In other aspects of the horn, proper square, glue amount, clamp pressure, all amounting to not unnecessarily forcing a panel to warp during clamping. all this plays HEAVILY into the sound of a BLH. All this infinite variance though is scientifically frustrating enough to make any (relative) perfectionist like me go insane. All these considerations make me want to apprentice for a violin or harpsichord maker. Not that they would by definition know any better, but these sorts of things are hard to model, and hard to know the ultimate effect of without the hundreds of years of trial and error tweaking that musical instruments have been subjected to.
Also, I am wondering people's opinions on various driver mounting methods (t-nuts, screws, driver on the front of the baffle, on mounted on the back of the baffle, etc.)
alot of these little tweaks most manufacturers keep rather secret, as frankly, they are the hardest learned lessons (that is, if they even think about these sorts of considerations in the first place...) so I hope that people will step out for a minute and share advice.
anyways, thanks in advance for the hopeful discussion this will start.
Later,
Clark
blumenstein-ultra-fi.com
finish.
my finish is a polymerized linseed oil. hand rubbed, no solvents. It is called "tried and true" varnish oil.
i think it sounds good. I am sure that there are other options though, acoustically speaking. health wise speaking, I stick with the non toxics. one of our stronger theories for why my old boss Terry Cain RIP got ALS (lou gehrig's disease) was that working for 30+ years with heavy metal and solvent laden finish products damaged his nervous system. while there are no truely conclusive studies to this effect, ones like this seem to point in a general direction. I mean, the stuff usually talks about nervous system damage on the can.
http://query.nytimes.com/gst/fullpa...934A35753C1A9619C8B63&sec=&spon=&pagewanted=2
So I guess I am wondering about people's experiences with the acoustic viability of various finishes, and whether or not people finish the insides of their speakers, and why or why not.
Clark
my finish is a polymerized linseed oil. hand rubbed, no solvents. It is called "tried and true" varnish oil.
i think it sounds good. I am sure that there are other options though, acoustically speaking. health wise speaking, I stick with the non toxics. one of our stronger theories for why my old boss Terry Cain RIP got ALS (lou gehrig's disease) was that working for 30+ years with heavy metal and solvent laden finish products damaged his nervous system. while there are no truely conclusive studies to this effect, ones like this seem to point in a general direction. I mean, the stuff usually talks about nervous system damage on the can.
http://query.nytimes.com/gst/fullpa...934A35753C1A9619C8B63&sec=&spon=&pagewanted=2
So I guess I am wondering about people's experiences with the acoustic viability of various finishes, and whether or not people finish the insides of their speakers, and why or why not.
Clark
At this very moment I am listening to a pair of five year old FE167E MLTL's. They have suffered temporary storage in an un-air conditioned garage in central Arkansas, been indoors for the heating season, been dragged to Dallas, Tulsa and Atlanta in the back of a pick-up and been rained on once. They show no sign of structural or cosmetic damage.
The insides are not sealed. That would be a little hard to do anyway, as I use a sandwich construction of MFD/"Liquid Nails"/HardiBacker.
I've tried a lot of different finishes: tung oil, "Danish" oil, acrylic, polyurethane and others. I get the best results with Minwax "Tung Oil Finish". My technique: Sand to 220 grit. Apply any stain and then a heavy coat of finish that saturates but not quite runs. Buff with 0000 steel wool and apply another coat of finish. This coat needs only be heavy enough to wet the surface. Repeat. Three coats is usually enough for a nice eggshell finish, although the grain may not be completely filled, particularly on oak and mahogany. For a super nice finish, apply a fourth coat, wait a week, wet sand lightly with 600 grit, then buff with white polishing compound.
Bob
The insides are not sealed. That would be a little hard to do anyway, as I use a sandwich construction of MFD/"Liquid Nails"/HardiBacker.
I've tried a lot of different finishes: tung oil, "Danish" oil, acrylic, polyurethane and others. I get the best results with Minwax "Tung Oil Finish". My technique: Sand to 220 grit. Apply any stain and then a heavy coat of finish that saturates but not quite runs. Buff with 0000 steel wool and apply another coat of finish. This coat needs only be heavy enough to wet the surface. Repeat. Three coats is usually enough for a nice eggshell finish, although the grain may not be completely filled, particularly on oak and mahogany. For a super nice finish, apply a fourth coat, wait a week, wet sand lightly with 600 grit, then buff with white polishing compound.
Bob
finsh
It depends on whut I'm building.
How inert do you want the cabinet to be?
I've tried polys, varnish, lacquer, shellac, linseed oil blends (tung oil, etc.) and inside, tar undercoating.
If you’re gonna be building cabs professionally, try building a few identically, then finishing them differently. It can make a difference.
On sealed subs I go for inert, may go for a constrained layer of concrete backer-board, and then use tar based automotive undercoating inside.
I haven’t built any horns yet, that’s next, but I plan to start doing the same as BLHs.
Back loaded horns I like to shellac the inside.
And sometimes It’s a pain, like the small parts of a Swan, ya know?
Why? Because people say I’m crazy, it sounds better
I don’t know why. Wood resonates different? Waves travel different?
Robert
It depends on whut I'm building.
How inert do you want the cabinet to be?
I've tried polys, varnish, lacquer, shellac, linseed oil blends (tung oil, etc.) and inside, tar undercoating.
If you’re gonna be building cabs professionally, try building a few identically, then finishing them differently. It can make a difference.
On sealed subs I go for inert, may go for a constrained layer of concrete backer-board, and then use tar based automotive undercoating inside.
I haven’t built any horns yet, that’s next, but I plan to start doing the same as BLHs.
Back loaded horns I like to shellac the inside.
And sometimes It’s a pain, like the small parts of a Swan, ya know?
Why? Because people say I’m crazy, it sounds better
I don’t know why. Wood resonates different? Waves travel different?
Robert
Re: finsh
If you are working in 15mm BB or thinner, sure the wood resonates. Will a soaking in shellac tone it down? Probably, but not like the finish on a violin will. The violin is much thinner.
In my case, i seriously doubt that the finish has any effect at all. The box is dead to begin with.
It is interesting that you think that damping your cabinets improves the sound. I have always thought that and have taken it to the extreme.
Bob
serenechaos said:
If you are working in 15mm BB or thinner, sure the wood resonates. Will a soaking in shellac tone it down? Probably, but not like the finish on a violin will. The violin is much thinner.
In my case, i seriously doubt that the finish has any effect at all. The box is dead to begin with.
It is interesting that you think that damping your cabinets improves the sound. I have always thought that and have taken it to the extreme.
Bob
I don't think damping improves the sound in all cabs.
I went go extremes in things like the sealed box mentioned above.
The walls of a BLH are another matter.
My experiments (and ears) may differ from yours, and thus our opinions differ.
That's why I suggest clark try for himself, and test with HIS ears.
Robert
I went go extremes in things like the sealed box mentioned above.
The walls of a BLH are another matter.
My experiments (and ears) may differ from yours, and thus our opinions differ.
That's why I suggest clark try for himself, and test with HIS ears.
Robert
I agree that you have to be careful with damping to make sure you don't suck the life out of the music. This is just as much an art , with lots of trial and error as most anything else in audio.
With stuffing and interior treatments like Black Hole 5 and others you can add or remove pieces until you find a nice balance. With oils and tar and other things that soak in, once it's done you can't remove it - so experience plays a big role there. If you want to get crazy I bet you will find that what works best in a bass or midrange cabinet is not the same as what works best for a tweeter.
Good luck,
Bob
With stuffing and interior treatments like Black Hole 5 and others you can add or remove pieces until you find a nice balance. With oils and tar and other things that soak in, once it's done you can't remove it - so experience plays a big role there. If you want to get crazy I bet you will find that what works best in a bass or midrange cabinet is not the same as what works best for a tweeter.
Good luck,
Bob
Resonance
Hello folks:
I have built a few cabinets over the last few years my techniques are a bit different from some people. I will attempt to describe some of the concepts I try to incorporate in my builds.
First and foremost I believe everything has a frequency of resonance. Differing materials resonate at differing frquencies.
Secondly I do not think you can eliminate resonance. I do think you can manage it though or at least influence it.
I think you want build as solidly as possible to deal with the simple stuff. So use good wood working skills and use the best joinery posible. Your enclosure is not a musical instrument it is an instument to reproduce as accurately as possible the music you are feeding it. It is not part of the music. This is not an easy concept for all to accept. But you really are not building a piano here.
Next use complicated materials that have good tensile strength and inherently low resonance. Baltic Birch plywood, dense fine grain real wood, bonded materials. The list is long. MDF or chip board is not really on the preferred list of materials.
Next try to make as small a panel as possible to reduce the flapping drum effect from large surfaces. If you look at Planet10 designs you will see lots of bracing in his designs. He is attempting to reduce the flapping drum effect in the cabinet walls. The concept here is to accept you are going to get some resonance, try to minimize the panel size and push the frequency up above the frequencies of interest. There are damping materials you can use but I am not familiar with them. I think Borosilicate is used by one manufacterer and I suspect the silent running product dave is using on drivers will also help.
there you go
Nuff said for now
Hello folks:
I have built a few cabinets over the last few years my techniques are a bit different from some people. I will attempt to describe some of the concepts I try to incorporate in my builds.
First and foremost I believe everything has a frequency of resonance. Differing materials resonate at differing frquencies.
Secondly I do not think you can eliminate resonance. I do think you can manage it though or at least influence it.
I think you want build as solidly as possible to deal with the simple stuff. So use good wood working skills and use the best joinery posible. Your enclosure is not a musical instrument it is an instument to reproduce as accurately as possible the music you are feeding it. It is not part of the music. This is not an easy concept for all to accept. But you really are not building a piano here.
Next use complicated materials that have good tensile strength and inherently low resonance. Baltic Birch plywood, dense fine grain real wood, bonded materials. The list is long. MDF or chip board is not really on the preferred list of materials.
Next try to make as small a panel as possible to reduce the flapping drum effect from large surfaces. If you look at Planet10 designs you will see lots of bracing in his designs. He is attempting to reduce the flapping drum effect in the cabinet walls. The concept here is to accept you are going to get some resonance, try to minimize the panel size and push the frequency up above the frequencies of interest. There are damping materials you can use but I am not familiar with them. I think Borosilicate is used by one manufacterer and I suspect the silent running product dave is using on drivers will also help.
there you go
Nuff said for now
Yeah, this one’s often hotly debated.
That’s why I started with “How inert do you want the cabinet to be?”
There seems to be two schools of thought there, the common one is that of course resonance should be eliminated as much as possible.
That the speaker cabinet is supposed to reproduce sound, not produce any sound (only the driver is to produce sound).
This school calls any sound produced by cabinet walls resonating “distortion.”
I built a pair of “end tables” with 18” Linkwitz Transformed drivers according to this school.
Doubled ¾” Baltic Birch, extensive matrix bracing inside (horizontal & vertical), with hardi-backer board glued inside as a constrained layer, ¾” x 4” oak legs, & top…
No “flapping drum.”
Some people even use concrete…
So, are these extreme’s the ultimate?
I dunno, but I sure don’t think so.
Yes, everything has a resonate frequency.
Put your ear on concrete, rap your knuckles and you can hear the vibrations.
Some frequencies will transmit through different mediums better than others.
But, the energy put in,
Will come out,
Sooner,
or,
Later.
That’s the other schools argument, (as I understand it), which I find so difficult to wrap my head around.
That a more damped cabinet, just holds the energy (resonance) in longer before releasing it.
So the distorted “additional sound” of the cabinets’ resonance is just added a few milli-seconds later than it would have been otherwise.
Clark,
You were @ RMAF, did you see that huge list of different cabinet materials & resonate frequencies one of the exhibitors had down stairs?
Did you catch the Micropure Cz-302ES?
Tiny little Japaneese speaker, handmade of hardwood, (no stinking veeners or sandpaper).
Thin, really thin walls.
And the driver was lightly mounted to the front baffle by small points, like a violn bridge.
That was his reasoning.
(They sounded so good I kept coming back, and talked to the owner/designer of the company as much as our language skills would allow).
Break all the “rules” I “knew”, but they sound awsome…
http://www.audioasylum.com/audio/speakers/messages/25/257616.html
Onkyo's doing something similar:
http://www.us.onkyo.com/detail_showstory.cfm?class=Speaker&m=D-TK10&p=i
Robert
That’s why I started with “How inert do you want the cabinet to be?”
There seems to be two schools of thought there, the common one is that of course resonance should be eliminated as much as possible.
That the speaker cabinet is supposed to reproduce sound, not produce any sound (only the driver is to produce sound).
This school calls any sound produced by cabinet walls resonating “distortion.”
I built a pair of “end tables” with 18” Linkwitz Transformed drivers according to this school.
Doubled ¾” Baltic Birch, extensive matrix bracing inside (horizontal & vertical), with hardi-backer board glued inside as a constrained layer, ¾” x 4” oak legs, & top…
No “flapping drum.”
Some people even use concrete…
So, are these extreme’s the ultimate?
I dunno, but I sure don’t think so.
Yes, everything has a resonate frequency.
Put your ear on concrete, rap your knuckles and you can hear the vibrations.
Some frequencies will transmit through different mediums better than others.
But, the energy put in,
Will come out,
Sooner,
or,
Later.
That’s the other schools argument, (as I understand it), which I find so difficult to wrap my head around.
That a more damped cabinet, just holds the energy (resonance) in longer before releasing it.
So the distorted “additional sound” of the cabinets’ resonance is just added a few milli-seconds later than it would have been otherwise.
Clark,
You were @ RMAF, did you see that huge list of different cabinet materials & resonate frequencies one of the exhibitors had down stairs?
Did you catch the Micropure Cz-302ES?
Tiny little Japaneese speaker, handmade of hardwood, (no stinking veeners or sandpaper).
Thin, really thin walls.
And the driver was lightly mounted to the front baffle by small points, like a violn bridge.
That was his reasoning.
(They sounded so good I kept coming back, and talked to the owner/designer of the company as much as our language skills would allow).
Break all the “rules” I “knew”, but they sound awsome…
http://www.audioasylum.com/audio/speakers/messages/25/257616.html
Onkyo's doing something similar:
http://www.us.onkyo.com/detail_showstory.cfm?class=Speaker&m=D-TK10&p=i
Robert
Well I have a total solution to cabinet resonances, get rid of the cabinet altogether.....
Go open baffle with the drivers not mounted to the cabinet/baffle but rather on a spiked support frame, that just slips in behind the baffle, into a hole cut just the right size for the driver and make sure the frame is firmly held in place, say with a sand bag or similar.
This is roughly how my system is constructed and the sound is very very clean, in fact it was not until I did this that I realized just how much cabinets and baffles of all types colour the sound.
All I hear now is music. Its all OBs for me, any box I have tried since going OB sounds like, well, a box!
Go open baffle with the drivers not mounted to the cabinet/baffle but rather on a spiked support frame, that just slips in behind the baffle, into a hole cut just the right size for the driver and make sure the frame is firmly held in place, say with a sand bag or similar.
This is roughly how my system is constructed and the sound is very very clean, in fact it was not until I did this that I realized just how much cabinets and baffles of all types colour the sound.
All I hear now is music. Its all OBs for me, any box I have tried since going OB sounds like, well, a box!
Yeah too true Dave, but it sure kills the issue stone dead.
I am lucky I guess as I have a room dedicated to my hi fi so the WAF and size is not an issue, the cost is pretty good though.
I have tried all sorts of cabinets, one set I built are actually about 90kg each and even they have resonances, though well controlled.
I am lucky I guess as I have a room dedicated to my hi fi so the WAF and size is not an issue, the cost is pretty good though.
I have tried all sorts of cabinets, one set I built are actually about 90kg each and even they have resonances, though well controlled.
Now I would love to hear about those OB projects.
I have tried a few OB set-ups, strangely enough the most musical, cleanest and detailed set-up uses the smallest drivers, a pair of very modded 4" twin cones with sealed 12 inch subs and piezos crossed in up high. (Not the loudest mind you, but then my head-banging days have past)
This set-up is driven by just 5 watts of battery powered gainclones, so there is no worries with efficiency.
Larger main drivers just seem ponderous by comparison. To my mind 4 to 5 inches is the sweet spot for real music.
Now since my 4 inchers are modded in a similar fashion to your FE127eN, (I think about 18 mods per driver from memory) it really has me wondering just how good might your FE127eN's be on a good open baffle with sealed subs etc. I imagine quite stunning.
It also has me wondering how much better might I be able to make mine.
Dave you really have me re-examining things too in regard to the eN mods, in fact I am about to try that on some Foster 103s I have sitting around plus I am ordering some other 4 inch drivers that are a lot like 103s but with bigger magnets (I have modded these successfully before).
My open baffle set-up is arranged so I can just pop different drivers into the system at will so testing is easy, thankfully.
Cheers
Zero One
I have tried a few OB set-ups, strangely enough the most musical, cleanest and detailed set-up uses the smallest drivers, a pair of very modded 4" twin cones with sealed 12 inch subs and piezos crossed in up high. (Not the loudest mind you, but then my head-banging days have past)
This set-up is driven by just 5 watts of battery powered gainclones, so there is no worries with efficiency.
Larger main drivers just seem ponderous by comparison. To my mind 4 to 5 inches is the sweet spot for real music.
Now since my 4 inchers are modded in a similar fashion to your FE127eN, (I think about 18 mods per driver from memory) it really has me wondering just how good might your FE127eN's be on a good open baffle with sealed subs etc. I imagine quite stunning.
It also has me wondering how much better might I be able to make mine.
Dave you really have me re-examining things too in regard to the eN mods, in fact I am about to try that on some Foster 103s I have sitting around plus I am ordering some other 4 inch drivers that are a lot like 103s but with bigger magnets (I have modded these successfully before).
My open baffle set-up is arranged so I can just pop different drivers into the system at will so testing is easy, thankfully.
Cheers
Zero One
OBs far from guarantee good sound. 
Many like them, but I've yet to hear one I like, & I've heard a lot of them.
They sound too unnatural, with that extra, delayed wave bouncing off the back wall. Just sound wrong to me.
I broke-in the 108ESRIIs in various size OBs before building Swans. Best OBs I've had, but the Swans are much better.
Robert
Many like them, but I've yet to hear one I like, & I've heard a lot of them.
They sound too unnatural, with that extra, delayed wave bouncing off the back wall. Just sound wrong to me.
I broke-in the 108ESRIIs in various size OBs before building Swans. Best OBs I've had, but the Swans are much better.
Robert
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